Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Magnon circular birefringence: Polarization rotation of spin waves and its applications

01.08.2017

An international team of researchers from Thailand, USA and Japan, has conducted a thorough study of an exotic behavior of material called "noncentrosymmetric antiferromagnet."The team, monitoring the behavior of the propagation of spin waves in magnetic material, has reported its findings [1], which show, for the first time, direct evidence of the nonreciprocal magnons.

A "circular birefringence" effect, where photons travelling inside a certain kind of crystal have different speeds depending on their circular polarization is fairly common. In other words, left-handed photons might travel faster than right-handed photons. Such an effect specifically appearing under a finite external magnetic field is the Faraday effect, where light polarization rotates as it propagates along the crystal with the rotation angle linearly depending on the field.


Fig. 1: Linearly polarized states of observed antiferromagnetic spin waves. The polarization angle changes in space, which indeed is an analogous effect to the 'circular birefringence' of light.

Credit: Taku J Sato


Fig. 2: Observed spin-wave dispersion relations and corresponding spin fluctuations in the circularly polarized states.

Credit: Taku J Sato

There have been tremendous applications of this effect in modern optical and photonic technology. Optical isolator is one of such devices using the Faraday effect, whereas magneto-optical recording is based on its reflection variant, the Kerr effect.

Other systems also exhibit behaviors that resemble the circular birefringence effect. In an ordered magnetic material, a spin excitation can also propagate along the crystal. This excitation is called a "magnon." Similar to the polarization states of photons, magnons in an antiferromagnet also have two distinct states: left-circular and right-circular state.

In most magnetic material, these two states have the same energy and are therefore indistinguishable. However, in a certain type of magnetic material, these two states of magnons behave differently due to a lack of spatial inversion symmetry in the crystal structure.

This phenomenon, called nonreciprocal magnons, has been predicted by Hayami et al. [2] However, there has been no direct observation of these nonreciprocal magnons until this work.

The research team performed neutron scattering experiments on single-crystal α-Cu2V2O7 and showed clear evidences of different energy-momentum dispersion relations between the left-circular and right-circular magnon propagation. The experimental data is confirmed by linear spin-wave calculations.

This work opens up a new regime of magnetic material which might find applications in magnon-based electronics (magnonics) such as the spin-wave field-effect transistor [3].

###

[1] G. Gitgeatpong, Y. Zhao, P. Piyawongwatthana, Y. Qiu, L. W. Harriger, N. P. Butch, T. J. Sato, and K. Matan, Phy. Rev. Lett. 119, 047201 (2017).

[2] S. Hayami, H. Kusunose, and Y. Motome, J. Phys. Soc. Jpn. 85, 053705 (2016).

[3] R. Cheng, M. W. Daniels, J.-G. Zhu, and D. Xiao, Sci. Rep. 6, 24223 (2016).

Taku J Sato | EurekAlert!

Further reports about: crystal structure magnetic field magnetic material photons polarization waves

More articles from Physics and Astronomy:

nachricht Unconventional superconductor may be used to create quantum computers of the future
19.02.2018 | Chalmers University of Technology

nachricht Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>